[PATCH v4 10/10] usb: gadget: uvc: add min g_ctrl vidioc and set min buffs to 4

[Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>]

We increase the minimum amount of v4l2 buffers that will be possibly
enqueued into the hardware and allocate at least
UVCG_STREAMING_MIN_BUFFERS amount of requests. This way the driver has
also more requests available to prefill the isoc hardware with.

Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>

---
v3 -> v4: -
v1 -> v3: new patch
---
 drivers/usb/gadget/function/uvc.h       |  2 ++
 drivers/usb/gadget/function/uvc_queue.c |  3 ++-
 drivers/usb/gadget/function/uvc_v4l2.c  | 13 +++++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h
index f6bc58fb02b84..e0b1f78fdbc65 100644
--- a/drivers/usb/gadget/function/uvc.h
+++ b/drivers/usb/gadget/function/uvc.h
@@ -71,6 +71,8 @@ extern unsigned int uvc_gadget_trace_param;
 
 #define UVCG_REQUEST_HEADER_LEN			12
 
+#define UVCG_STREAMING_MIN_BUFFERS		4
+
 /* ------------------------------------------------------------------------
  * Structures
  */
diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.c
index e33ce72325031..157e7f7d49c7a 100644
--- a/drivers/usb/gadget/function/uvc_queue.c
+++ b/drivers/usb/gadget/function/uvc_queue.c
@@ -21,6 +21,7 @@
 #include <media/videobuf2-vmalloc.h>
 
 #include "uvc.h"
+#include "uvc_video.h"
 
 /* ------------------------------------------------------------------------
  * Video buffers queue management.
@@ -86,7 +87,7 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 	}
 
 	video->req_size = req_size;
-	video->uvc_num_requests = nreq;
+	video->uvc_num_requests = nreq * UVCG_STREAMING_MIN_BUFFERS;
 
 	return 0;
 }
diff --git a/drivers/usb/gadget/function/uvc_v4l2.c b/drivers/usb/gadget/function/uvc_v4l2.c
index 392fb400aad14..f96074f2c2824 100644
--- a/drivers/usb/gadget/function/uvc_v4l2.c
+++ b/drivers/usb/gadget/function/uvc_v4l2.c
@@ -357,6 +357,18 @@ static int uvc_v4l2_s_parm(struct file *file, void *fh,
 	return 0;
 }
 
+static int uvc_g_ctrl(struct file *file, void *priv, struct v4l2_control *vc)
+{
+	int ret = -EINVAL;
+
+	if (vc->id == V4L2_CID_MIN_BUFFERS_FOR_OUTPUT) {
+		vc->value = UVCG_STREAMING_MIN_BUFFERS;
+		ret = 0;
+	}
+
+	return ret;
+}
+
 static int
 uvc_v4l2_enum_frameintervals(struct file *file, void *fh,
 		struct v4l2_frmivalenum *fival)
@@ -629,6 +641,7 @@ const struct v4l2_ioctl_ops uvc_v4l2_ioctl_ops = {
 	.vidioc_streamoff = uvc_v4l2_streamoff,
 	.vidioc_s_parm = uvc_v4l2_s_parm,
 	.vidioc_g_parm = uvc_v4l2_g_parm,
+	.vidioc_g_ctrl = uvc_g_ctrl,
 	.vidioc_subscribe_event = uvc_v4l2_subscribe_event,
 	.vidioc_unsubscribe_event = uvc_v4l2_unsubscribe_event,
 	.vidioc_default = uvc_v4l2_ioctl_default,

-- 
2.39.2